Summary of this, while keeping any information that looks important? "Internally, Christianity was seriously divided between the Roman Catholics of Western and Central Europe and the Eastern Orthodox of Eastern Europe and Russia. Externally, it was very much on the defensive against an expansive Islam. Muslims had ousted Christian Crusaders from their toeholds in the Holy Land by 1300, and with the Ottoman seizure of Constantinople in 1453, they had captured the prestigious capital of Eastern Orthodoxy. The Ottoman siege of Vienna in 1529 marked a Muslim advance into the heart of Central Europe. Except in Spain, which had recently been reclaimed for Christendom after centuries of Muslim rule, the future, it must have seemed, lay with Islam rather than Christianity."